Ignition apparatus



Jan. 7, 1941. c. HOOD ETAL IGNITION APPARATUS Filed Jan. 7, 1939 n o d my 5 om n p w R t m s t W1 h m m LI. T

I @o l .W. .0 Q P Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE IGNITION- APPARATUS Application January 7, 1939, Serial No. 249,784 In Great Britain May 9, 1938 5 Claims. (Cl. zoo-49f This invention relates to ignition apparatus for internal combustion engines and more particularly for multi-cylinder aircraft engines. The object of this invention is to provide an 5 improved apparatus for obtaining satisfactory ignition at high altitudes.

In the usual type of ignition apparatus employing a jump spark type of high tension distributor, it has been found that the altitude at 10 which the ignition apparatus will function satisfactorily, is limited by the tendency for the spark discharge from the distributor brush electrode to jump back to the distributor segment which has just carried the previous discharge in 15 preference to the correct oncoming segment. This causes missing on the particular engine plug connected to the segment with consequent loss of engine power.

It is an object of this invention to provide 20 means for insuring the correct sparking sequence in an ignition distributor.

It is a further object of this invention to pro vide a new and improved distributor rotor, particularly adaptable for use with aircraft engines 25 at high altitudes.

For a consideration of what we believe to be novel and our invention, attention is directed to the following description and the claims appended thereto taken in connection with the ac- 30 companying drawing.

The invention will be better understood by reference to the accompanying drawing in which Fig. 1 shows a section of a high tension distributor, Fig. 2 is a plan view of the same and Figs.

35 3 to 5 illustrate alternative forms of the invention.

Referring to Figs. 1 and 2, l represents a section of a high tension distributor provided with a plurality of circumferentially arranged 4O distributor terminals H, l2 and I3 which are connected to the appropriate spark plugs in the various cylinders. The rotating brush holder or rotor l4 carries the brush electrode I 5 which is connected to the coil of the ignition apparatus supplying the high tension voltage for distribution and is adapted to be rotated in close proximity to the distributor terminals. The brush I5 is usually a metal electrode and with such an arrangement it has been found that 50 with the brush holder l4 rotating in the direction shown, the spark from the electrode 15 will more readily jump back to the previous terminal I I at light atmospheric pressure rather than follow the very much shorter air path to termi- 55 nal I 2.

In the preferred embodiment of the invention shown in Figs. 1 and 2, a collar l6 of suitable insulating material is provided around the extremity of the distributor electrode l5, leaving but the end thereof exposed. This collar may be a separate member suitably secured onto the electrode of conventional design, or it may be molded integrally with the rotor body ll during the manufacture thereof. Tests have shown that the operational characteristics of the dis- 10 tributor have been greatly improved by this design, and that the proper sparking sequence was maintained at pressure corresponding to 1,000 to 10,000 feet increase in altitude, as compared with distributors of the heretofore known designs. The recurrence of arcing between the electrode and the terminal having received the previous discharge, as it was passed by the electrode, is substantially eliminated over an extended range of low atmospheric pressures.

Fig. 3 illustrates a modification in which the electrode sides only are covered with the insulating material IT. This arrangement overcomes the difficulty associated with burning, due to the discharge arc, of the surface of the insulation material at the rear of the brush. It is preferable for the insulation to extend slightly beyond the end of the electrode as shown in Fig. 4.

While it is preferred to use insulating material surrounding or partly surrounding the metal electrode as illustrated in Figs. 1 to 4, we have found that the desired effect can be produced to a lesser degree by the provision of metal pieces I B suitably secured to the sides of the electrode l5 as shown in Fig. 5. These side pieces extend slightly above the surface of the electrode.

The figures illustrate insulation or metal side pieces fitted to the rotating brush electrode but the invention is not limited to this arrangement as the desired efiect can be produced by providing the stationary distributor electrodes with insulating collars or side shields as described above.

Having described the principle of operation of our invention together with the apparatus which we now consider to represent the best embodi- 4:5 ment thereof, we desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In a distributor for ignition apparatus, a plurality of circumferentially arranged terminals,

a rotor having an electrode adapted to pass in close proximity of said plurality of circumferentially arranged terminals, and insulation substantially surrounding the sides of the extremity of said electrode for minimizing the recurrence of arcing between said electrode and the terminal having been passed by said electrode during rotation thereof in a relatively low pressure atmosphere.

2. In a distributor for ignition apparatus, a rotor having an electrode adapted to be rotated in close proximity of a plurality of circumferentially spaced terminals, means provided on the extremity of said electrode for minimizing the recurrence of arcing between said electrode and the terminal having been passed by said electrode during the rotation thereof in a relatively low pressure atmosphere.

3. In a distributor for ignition apparatus, a ro-' tor having an electrode adapted to be rotated in close proximity of a plurality of circumferentially arranged terminals, means provided on the sides of said electrode lying in planes parallel with the plane of the electrode rotation and extending slightly beyond the end of said electrode, said means enhancing the arcing between said electrode and. the adjacent terminal being passed by the electrode.

4. Ignition apparatus for internal combustion engines comprising a distributor having a rotor adapted to be driven by the engine, said rotor having an electrode adapted to be rotated past a plurality of circumferentially arranged terminals, and means surrounding said electrode for substantially precluding arcing between said electrode and a terminal other than that nearest said electrode.

5. Ignition apparatus for internal combustion engines comprising a distributor having a rotor adapted to be driven by the engine, said rotor having an electrode adapted to be rotated past a plurality of cireumferentially arranged terminals, and metallic means arranged along the sides of the electrode lying in planes parallel with the plane of the electrode rotation and extending slightly beyond the end of the electrode for minimizing the recurrence of arcing between said electrode and a terminal having been passed by 20 said electrode during the rotation thereof.

CHARLES HOOD. THOMAS F. ROBINSON. 

